Broadly, this invention is directed to the treatment of objects, particularly fluid containing subsurface strata or formations for the purpose of increasing the production of the fluids therefrom.
The concept of utilizing sonic waves and/or variable high frequency vibrations in the treatment of subsurface strata or formation is found in the prior art including but not limited to the early patents of Sherborne U.S. Pat. No. 2,670,101 and Bodine U.S. Pat. Nos. 2,355,618; 2,667,932; 2,871,943; 3,016,093; 3,016,095; and Reissue 23,381. These references have as a common denominator the creation and utilization of sonic standing waves, whether symmetrical or not which are repetitive or reoccurring without change, as a means of increasing oil recovery. As is typical of hydraulic fracturing of subterranean formations, the purpose was to apply substantially unidirectional application of fluid pressure and force against the formation until the formation yielded and fractured leaving vugular channels for the increased production and flow of the desired formation fluids.
The concept of methods and apparatus for creating sonic waves wherein the wave characteristics are variable or changeable at the will of the operator are found in many of the Clarence W. Brandon patents such as U.S. Pat. Nos. 3,981,624; 3,640,344; 3,045,749; 3,323,592; 2,866,509; 3,422,894; 3,302,720; 3,765,804; and 4,022,275. Brandon's concepts have been expanded and improved by the present invention.
For the purposes of this invention, Clarence W. Brandon, U.S. Pat. No. 3,981,624 issued Sep. 21, 1976 is incorporated herein by reference. In the aforesaid Brandon patent, the construction of the reciprocating pistons used in the sonic wave generator, i.e. the variable stroke pumping unit, sometimes referred to herein as "sonofrac machine" utilized a working plunger or piston which comprised a cylindrical member which was open at both ends yet divided by a partition. Reference is made to the description and specification relative to FIG. 33 of the aforesaid '624 patent. Immediately adjacent the partition and extending towards the forward end of the piston was a longitudinally extending slot which constituted the inlet port opening into the hollow interior of the piston. At the outer end of the piston was a valve chamber terminating in a conical valve seat with a spring loaded mushroom type valve normally closing the end of the piston. These pistons and their valves are internally operable to receive fluid under pressure capable of forcing fluid out against the spring loaded valve at a higher pressure and frequency. The variable stroke pump required that liquid medium, e.g. water and/or oil or other fluid, be delivered from a separate pump under sufficient pressure to enter the variable speed main pump piston along with and in conjunction with the movement of the piston.
A triplex type feed pump, i.e., a low speed/high pressure pump was provided as a means for delivering the fluid under pressure to the variable stroke sonofrac machine. It has been found to be important in treating subsurface formations that the energy generated by a sonofrac machine, such as found in the aforesaid Brandon patents, be directed away from the variable stroke pump generator into the formation with no part of that energy being lost or wasted, that is, that the energy not be allowed to reverberate back into the generating machine, or back to the feed pump.
The triplex feed pump was connected to an adjoining water tank with a supply or suction line for the source of liquid. Delivery of water from that tank into the piston of the triplex pump depended upon the very slight pressure exerted by the head or weight of water in the supply tank. In many instances this pressure was inadequate to overcome friction and resistance from the supply tank and suction inlet piping. Consequently, the cylinders of the triplex pump were not filled, and in some instances cavitation of the triplex pump occurred during operation. In other instances reflective or refractive energy waves from the sonofrac machine would disrupt the operation of the feed pump. As a result, the triplex pump was known to become damaged during tests and in any event was incapable of delivering sufficient water either in quantity or pressure to the variable stroke pump described in the aforesaid Brandon patent which has been incorporated by reference herein.
In addition, the Brandon sonofrac machine taught circulation of fluid from and between the two main piston pumps 100 and 101 and related cavitation valves to enhance pressures and wave formation, etc.. It has been found that this type of interconnected fluid circulation system created reverberations that tended to cancel system pressures, wave formation, etc.
Similarly, the connection of the two cavitation valves 82 to a single discharge line created similar cancellation and dampening of the enhanced pressures and enhanced wave energy which the valves were otherwise intended to produce upon the pressures and wave energy produced by the main pumps 100 and 101.
Brandon's prior design of the plungers in pumps 100 and 101 used plungers with cavities (side inlets) and discharge valves acting as their ends to allow fluid to pass from those plungers during reverse strokes--then for the discharge valves to close and compress fluid forward of the plungers during their forward strokes. This imparted action to the column of fluid beyond the pump plungers producing wave forms, etc.
However, those pumps were redesigned by Brandon, their plungers revised from 2" diameter to 4" diameter with inlet openings at the rear of the main plunger bodies, instead of the side inlet openings. When the pump plungers are forced in reverse against fluid delivered to their cylinders from feed pump 26, a compressive force was delivered against the supply of fluid delivered from feed pump 26.
The Brandon style of pumps did not include check valves used as inlet valves to close against the reverse action, and as a result, pumps 100 and 101 could not ratchet increasing pressure. That is, the intake openings of pumps 100 and 101 were connected by a common line to the conduit from feed pump 26 which allowed fluid to oscillate between the pumps. As such, the reverse action of pump plungers might deliver as much force back against pump 26 as they might deliver ahead.